It has been recently announced that, from telescopic observations, the atmosphere of Mars must be at least as attenuated as that among the highest mountainous regions of the earth, if this planet has any atmosphere at all. That it must be far less dense than that of the earth at sea-level is obvious, for the mass and volume of Mars are very much less than those of our own planet; but that Mars is devoid of a gaseous envelope or atmosphere is contrary to what we know of all sidereal physics. The sun, the fixed stars, the comets, the nebulæ, and even the meteorolithic fragments which fall upon the earth, all show the same elementary chemical constitution as the earth itself, and we cannot believe that Mars alone is differently constituted from every other body we have been able to examine. We have direct evidence, on this planet, of polar snows and their melting away under the sun's heat; we see the apparent areas of sea and land; it has its moons as the earth has hers, and exhibits all the characteristic phenomena of the earth and other planets. All sidereal bodies that we know of, except, perhaps, our moon, which exception we have fully accounted for, are found to be surrounded by gaseous envelopes or atmospheres of some sort. The sun, the fixed stars, the nuclei of comets, the condensing nebulæ, the planets Jupiter and the earth, which are those under our most direct observation, and even the meteorites, when examined, reveal the presence of many times their own volumes of independent atmospheric gases; and whatever may be the theory of the origin or development of Mars, it must have been subjected to the same influences, the same environment, and the same processes of creation as those of our solar system generally; and that this body alone should possess no gaseous envelope--for the denial of atmosphere denies, at the same time, the presence of any or all surrounding gases--is quite incredible. Only the most positive, direct, and long-continued proofs of such fact could be accepted, and even then the history of all scientific progress shows that what are believed to be facts themselves fluctuate like fancies till, by their accumulated force, they solidify into universally accepted demonstration. The fact, moreover, that the atmospheres of the smaller planets are more attenuated than our own and those of the larger ones denser has no bearing, in itself, on the probability of the existence of life on these other planets, for in our own atmosphere oxygen, which is the efficient element, is diluted with four times its quantity of inert nitrogen. These proportions doubtless vary largely in other atmospheres, so that the oxygen may be much richer in some and far poorer, relatively, in others. The mere fact that the presence of nitrogen, probably, and aqueous vapor, certainly, depends on the gravity of the mass of each planet, while the oxygen is due to electrolytic decomposition induced